Gripper for wire tying machine



y 13, 1958 D. M. DANIEL 2,834,382

GRIPFER FOR WIRE mm; MACHINE Filed July 13, 1955 Fig.1-

f I: -6- 2s 5 INVENTOR.

DAV/D M. DAN/EL ATTORNEYS United States PatentO GRIPPER FOR WIRE TYING MACHINE -David M. Daniel, Berkeley, Calif., assignor to Ernest Roe,

doing business as Coast Wire Company, San Francisco, Calif.

This invention relates to new and useful improvements in gripper for wire tying machine. The wire tying machine with which this invention may be employed may be of the general type disclosed in U. S. Letters Patent No. 1,545,407, issued July 7, 1925 to C. L. Drew, et a1. Reference is also made to Patents 2,460,846; 2,580,848 and 2,624,375.

The wire tying machine with which this invention is employed comprises a portable tool constructed to rest upon a package or other object to be strapped and comprises means for twisting together a wire placed around the package to form a tie and means for cutting off the ends of the wire extending beyond the tie. An operating lever is provided which lever when manually moved from its normal position serves, first, to tighten the two ends of the wire by moving them in opposite directions and then, upon return of the operating lever toward neutral position, twists or ties the wire and finally cuts oil each end portion. Preliminary to manual actuation of the lever, the operator inserts the two ends of the wire in grippers, one on each side of the machine. The grippers hold the ends of the wire against displacement when strain is applied during tightening and twisting.

The present invention relates to the construction of one or both of the grippers employed to hold the wire.

A primary object of the present invention is to facilitate the insertion of the end of the Wire in the gripper. The present invention enables the operator to insert the end of the wire very rapidly and positively, without possibility of displacement. Thus, in previous wire tying machines it has been necessary to first insert the end of the wire through a slot in a twister pinion commonly employed in such machines and then through the gripper. This sequence of operations is time consuming and requires an awkward manual movement. In accordance with the present invention, the free end of the wire. may first be inserted through the gripper and then through the slot in the twister pinion :and through the openings between the cutting blades which subsequently'sever the end of the wire. The construction of the gripper and tis mounting, hereinafter described, enables the wire to be inserted. through the gripper at an angle and this greatly facilitates and speeds the operation.

Another principal object of the invention is the provision of a gripper which provides a more positive and more durable grip. This result is accomplished 'by the location of a plurality of gripper teeth on a gripper plate, which plate is pivotally mounted on a support and counter-weighted in such manner that the force of gravity tends to bring the teeth of the gripper into contact with the wire to be tied and,.as the-tightening of the ends of the wire is accomplished, tends to grip one of the ends more tightly as the tension is increased.

The. gripper employed in connection with the present invention actually consists of two sets of gripper teeth which may be used serially when one set has become dull. However, the two sets .of. teeth cooperate with each other in that the teeth are formed on the opposite legs of a U-shaped plate and are so positioned and arranged with respect to each other and with respect to the point of pivotal attachment of the plate to its support that the weight of the leg not in use cooperates in bringing the teeth of the leg in use into contact with the end of the wire being tightened.

Grippers in the prior art have frequently been dependent for their operation in whole or in part upon springs or similar tensioning means to cause the gripping element to hold the wire against an underlying bed. The present invention employs no such spring or other tensioning device and hence deterioration or breakage of the spring does not interfere with operation of the tool.

Another advantage of the invention is the absence of more than one moving part in the gripper.

Other objects of the present invention will become apparent upon reading of the following specification and referring to the accompanying drawings in which similar characters of reference represent corresponding parts in each of the several views.

In the drawings:

Fig. 1 is a front elevation of a portion of a wire tying machine in which the gripper which comprises the present invention is installed on the left side.

Fig. 2 is a view similar to Fig. 1 showing the position of the machine subsequent to insertion of the wire butprior to the twisting operation.

Fig. 3 is a front elevation of the gripper showing the position of the parts as the wire is being inserted.

Fig. 4 is a vertical section taken substantially along line 4--4 of Fig. 3.

Fig. 5 is a perspective of the gripper showing the Wire after insertion.

Fig. 6 is a bottom plan of a preferred form of gripper.

The instant invention as particularly illustrated and described with reference to the use of flat steelwire straps, but it is understood that it may be used to grip round wire of standard types.

As hereinafter described, the gripper which is the subject of this invention and which is installed on the left side of the machine as viewed in Figs. 1 and 2, is utilized with a suitable wire tying machine of the general type as disclosed in United States Letters Patent No. 1,545,407 dated July 7, 1925, issued to C. L. Drew, and with certain improvements thereof disclosed in Patents 2,460,846; 2,580,848 and 2,624,375.

Such a machine may be employed to tie a package 10 by means of wire 11, which wire is Withdrawn from a coil (not shown) on the right hand side of the machine and is first manually pulled through right gripper 1 2, which is mounted on right support 15 and then through an opening 13 in the right cut-ofi blade 14 and then through a radially disposed slot 16 in the twister pinion 17 and twister pinion guide mechanism 18. Thereafter the end of the wire is brought up through a retaining slot 19, around under the package 10 and up to the top. The'instantinvention relates to means of gripping the free end of the'wire 11. Such free end is first gripped in the left gripper 21 and then inserted in slot 16 in the pinion 17 and in guide mechanism 18 and slot 22 in left cutter blade 23 employed in the instant machine.

The mechanism whereby the machine operates first to tighten the ends of the wire 11 by pulling them in opposite directions, then to twist the wire to form a tie and finally to cut oil the ends of the wire is fully described in the patents to which reference has been made.

It will be understood that the left gripper 21 ismounted uponva support 26 which support is actuated during the-course of the tightening operation to move to the left as viewed in Figs. 1 and 2, thereby tightening the end of the wire. After the wire has been tied, support 2:; retracts to its normal position as illustrated in Figs. 1 and 2. The left gripper 21 comprises a thin U-shaped plate 27 with a set of gripper teeth 23 on the lower end of each of the legs of the U. .The thickness of the front working face of each of the legs of the U. is reduced as shown particularly by reference numeral 29 in Fig. so that the thickness of the end of the plate 27 is substantially equal to the width of the flat wire 11 being tied. A hole 31 is formed in the upper end of each leg of plate 27 through which projects a pivot 32 which is screwed into the support 26. Thus, the weight of the opposite end of plate 27 tends to rotate the gripper in a counter-clockwise direction. A horizontal pin 33 is sunk in support 26 adjacent the lower end of the working leg of plate 27, the end of the wire being received between the pin 33 and the teeth 28 on the bottom face of the plate. wise direction tends to clamp the wire between teeth 28 and pin 33.

It will be noted that the lower end of each leg of plate 27 is formed with serrations or teeth 28 which assist in gripping the upper surface of the wire. The bottom of the leg of the gripper is formed at an angle of about 15 with the horizontal upwardly from left to right when viewed from the front. The ends of the teeth lie along an are having a long radius of curvature. The teeth 28 are formed substantially V-shaped and positioned so that a line drawn through the vertex of the V is substantially normal to the are along which the lower end of the leg is formed.

Between the two legs of plate 27 a guide 36 is secured by screw 37 to support 26, and depends substantially vertical at a distance from the face of support 26 equal to the width of the wire being tied. Guide 36 prevents outward displacement of the end of the wire.

Support 26 is recessed to the left of pin 33 as indicated by numeral 38 but in all other parts of support 26 the working face is substantially smooth and parallel to the direction the wire assumes as it is being tied. As shown particularly in Fig. 4 (which shows the wire as it is being threaded into the gripper) recess 38 in support 26 assists in insertion of the end of the wire at an angle, for the end of the wire may project into recess 38 thus permitting angular insertion of the end of the wire between teeth 28 and pin 33. Recess 38 is to the left of pin 33 so that the front surface of support 26 directly above pin 33 cooperates in holding the wire in position to be gripped. Recess 38 extends higher than the elevation of the top of pin 33 so that when wire 11 is pushed over pin 33 it extends into the recess. After the wire has been inserted in the left gripper 21, pinion slot16 and slot 22, it assumes the position shown in Fig. 5 parallel to surface 26.

It will be understood that when the teeth 28 of one of the legs of the gripper plate 27 become worn, screw 32 may be removed, plate 27 turned around and the opposite leg employed. The weight of the left-hand end of plate 27 serves to bring the gripping teeth of the righthand end into contact with the top surface of wire 11.

One of the novel features of the present invention is the mounting of the plate 21. The central axis of pivot 32 is displaced slightly to the left of the central axis of stud 33 as viewed in Fig. 3. Thus, the weight of plate 21 tends to rotate plate 21 about pivot 32 as an axis and bring the teeth on the lower end of the working leg of the plate into contact with wire 11 above stud 33 at an abrupt angle which assists in securing a good gripping action.

Another feature of the invention is the preferred form of tooth shown particularly in Fig. 6. It will be seen that the teeth 28a may be formed helically rather than straight so that they come into contact with wire 11 at an angle thereto. Such a shape of tooth results in good gripping contact with the wire regardless of the angular displacement of plate 21 about pivot 32. Expressed in other terms, some portion of one or more teeth will contact and grip the wire 11 as soon as the lower end of the working leg engages wire 11 by reason of the fact that the teeth are angularly disposed with relation to the wire. If straight teeth are employed, then the result may be that one tooth does not quite contact the wire, whereupon the next tooth must grip the wire extremely hard, which creates the danger of breaking the wire. With the preferred form of tooth, portions of one or more teeth are continuously in contact with the wire. An advantage of the helical or angular arrangement of the teeth 28a is that, upon contact with the wire, a force is imparted to the wire which has a component tending to Rotation of the gripper plate 27 in counter-clockforce the wire against support 26. This component prevents the wire from slipping off stud 33.

In operation, the operator first brings a wire 11 drawn from a coil box (not shown) through the right gripper 12, thence through the opening 13 in the right cutter blade 14 and through the slot 16 in the pinion 17, through the left guide 19, then around under the package 10 and up to the top. The operator then inserts the wire through the gap 22 in the left cutting blade 23 and simultaneously inserts the end of the'wire between the lower end of the Working leg of plate 27 and pin 33. By reason of the pivotal mounting of plate 27 and its relationship to pin 33, when the end of the wire is forced on top of the pin, the top of the pin 33 directs the wire under the leg of plate 27 and the wire extends thence into recess 38 in support 26 and behind guide 36. Thereupon the operator brings the wire into slot 16 in the twister pinion 17 and the wire automatically straightens itself into proper position for commencement of the tying operation. It

. will be seen that the insertion of the wire in the left gripper 21 is easily and rapidly completed by use of the right hand of the operator.

The operator subsequently pulls the opposite ends of the wire apart manually so that the wire is tight around the package 10 and then pulls the operating lever (not shown) forwardly which spreads apart the supports 26 and 15 for the left and right gripper, respectively, thereby tightening wire 11 around package 10 and the operator then releases the operating lever which returns to position as it first twists the pinion 17 causing the tie to be made and then causes actuation of the cutter blades 14 and 23 which sever the ends of the wire.

The shape of the left gripper plate 27 and its relation with respect to pin 33 is such that the weight of the plate brings the teeth on the end of the working leg into contact with top surface of the wire and, as the wire is tightened and twisted, the teeth continue to grip the wire and hold the same against displacement. The center of pin 33 is off-set to the right a short distance from a vertical line passing through the center of the pivot 32 and this relationship and the angle and shape of teeth 28 likewise cause a firm grip on the wire.

Although I have described my invention in some detail by way of illustration and example for purposes of clarity of understanding, it is understood that certain changes and modifications may be practiced within the spirit of the invention and scope of the appended claim.

I claim:

A gripper for a wire tying machine comprising a support having a substantially flat, vertical surface extending parallel to the direction assumed by the wire to be tied, a horizontal pin in said support, a gripper plate, and means mounting said gripper plate on said support for pivotal movement parallel to said vertical surface of said support, said pin being positioned substantially directly below said mounting means, said gripper plate having a leg depending below said mounting means and a heavy portion positioned tending to rotate said plate about said mounting means to bring the lower end of said leg into contact with said pin, the lower end of said leg being formed with teeth disposed along the bottom of the lower end of said leg, said gripper plate having a central portion parallel to and in bearing contact with said vertical surface of said support for connecting said leg and heavy portion, the lawer end of said leg being disposed at an angle such that said teeth grip the top of a wire inserted over said pin, the vertical surface of said support being recessed beyond said pin in the direction opposite that of normal insertion of a wire, the recess extending upward to an elevation higher than the elevation of the top of said pin, and guide means connected on said support to prevent outward movement of said wire adjacent said recess.

References Cited in the file of this patent UNITED STATES PATENTS 

